This invention relates to devices used in the printing industry. More particularly, this invention relates to registration boards used to hold pre-press proofs and printing plates in proper alignment.
Registration board assemblies are known for laying out the proof of a page to be printed. A typical proof of a page, such as a magazine page, may have each article, photograph and the like set forth on its own single sheet of transparent film. If the magazine page has, for example, four articles and pictures, the proof may comprise four sheets.
Printing customers and the printers themselves often wish to view a proof of the page to be printed before the printing is performed. Since the proof may contain several sheets or layers, it is necessary to keep the layers properly aligned during the inspection. This is accomplished using a registration frame assembly having a frame structure, a registration board or a bottom layer with register pins protruding therefrom, and a glass or other transparent cover. The multiple sheets that comprise the pre-press proof page are aligned and placed on the register pins, and the cover of the registration board assembly is closed. A vacuum is then created in the closed registration frame assembly. The pre-press proof page may then be inspected with all the sheets or layers in their correct positions.
The register pin assemblies used in registration board assemblies are typically movable in the axial direction of the register pin so that the top of the register pin is flush with the proof page when the glass cover is closed. The register pin assembly moves in the axially downward direction when it is pressed by the glass cover, and moves in the axially upward direction when the glass cover is raised. The register pin assembly must typically be provided with a resilient elastomeric member to enable the pin to return to its original position.
After repeated use, however, the resiliency of the register pin assembly is often lost. The elastomeric member may lose its elasticity. In that event, it is often not possible to replace components of the register pin assembly without replacing the entire bottom layer and the entire register pin assembly.
Some prior art registration board assemblies used fixed or non-axially movable register pins in an effort to minimize the likelihood that the proof page layers will go out of alignment due to the axial movement of the register pin. Such prior art assemblies typically have a register pin securely mounted to a stiff planar registration board. A disadvantage of this design is that the registration board tends to split or break due to the repeated application of force from the glass cover on the register pin. The entire registration board and the register pin must then be replaced.